Horticulture Principles and Practices

pennsylvanica),

pennsylvanica), hackberry (Celtis spp.), American elm (Ulmus Americana), poplar (Populus spp.), willow (Salix spp.), sumac (Rhus spp.), and silver maple (Acer saccharinum). Species that are not tolerant of transplanting include walnut (Juglans spp.), oak (Quercus macrocarpa), and buckeye (Aesculus spp.). 17.14 PLANTING TREES The success of a transplanted tree seedling depends on the timing of planting, seedling preplanting preparation, soil preparation, and planting technique, among other factors. 17.14.1 TIMING Spring offers the best conditions for planting many tree species. The conditions at this time provide adequate moisture and warm soils for plant root establishment and growth. The relatively cool temperatures of spring minimize moisture loss through transpiration and thus reduce the incidence of transplanting shock. The cool temperatures of fall (in areas where winters are mild) also provide good conditions for planting trees. The limitation to planting under this condition is frozen soil. Many deciduous and evergreen broadleaf trees as well as conifers may be planted during this period. Planting in summer is most challenging because of the high temperatures and intense sunlight that induce rapid drying of plant tissue. Some container plants may be planted during this period but will require great care for success. 17.14.2 LOCATING PLANTS Trees live for a long time in the landscape. Mistakes in locating them can be costly. Locating plants in the landscape should be done very judiciously, taking into account structures like sidewalks, pavements, light posts, buildings, and the adult plant size and form. Trees should be located where they will have ample room for both root and crown to develop fully. The light conditions, soil pH, and soil moisture are critical factors to consider as well. 17.14.3 DIGGING THE HOLE Some general guidelines should be observed in digging a hole for planting trees. First, the hole should be large enough to contain the plant roots without the need to squeeze or pack them tightly. There should be ample room around the roots for soil to be added. The hole should be at least 12 inches wider than the ball of roots. The depth of the hole should be such that when the plant is set, the original soil level on the plant is maintained after filling the hole with soil. It should be about 6 inches deeper than the soil ball around the roots. The topsoil should be carefully piled up near the hole in a separate heap from the subsoil, which is called the backfill soil. This practice may not be possible when a tractormounted power take-off is used to dig the hole. 17.14.4 PLANT PREPARATION Bare-root plants should be sent to the field in a container of water to avoid drying roots. The roots are then carefully pruned before setting in the hole. In container plants, the potbound roots should be straightened and spread out before placing them in the hole. 17.14.5 PLANTING Bare-root plants need to be held while setting them in the hole. First, some backfill soil is placed in the hole. The plant is then held such that the crown is slightly above the soil level, and the hole is refilled with topsoil or, as some growers prefer, amended soil (soil mixed with organic matter and sometimes fertilizer). After filling, the soil should be packed firmly by tamping with a foot or stick, making sure the trunk remains erect (Figure 17–8). In the Backfill Soil Topsoil dug out of a hole and used to fill it during seedling transplanting. 17.14 Planting Trees 529

FIGURE 17–8 Planting a bareroot tree seedling. Backfill Berm Prune root if too long FIGURE 17–9 Planting a balled and burlapped tree seedling. Backfill Untie rope Cut away exposed burlap Cut burlap in several places case of burlapped seedlings, the ball is set in the hole before untying the ropes. A broken soil ball may result in the seedling’s death. The crown should also be set above the soil line. The burlap material is usually biodegradable and need not be removed before planting. Instead, only the overhanging top is trimmed off (Figure 17–9). The remainder of the space is filled with topsoil and patted firm. If the burlap material is not biodegradable, it must be removed by making a slit in the bottom of the wrapping and pulling it up after properly setting the seedling in the hole. Under no circumstances should a plant be planted at a depth lower than it was before transplanting. Plants are easily killed when seedlings are planted too deeply. It may be helpful to mark the original soil level on the seedling prior to transplanting. 17.15 POSTPLANTING IMMEDIATE CARE Newly planted tree seedlings require immediate care to increase the chance of successful establishment. This care package includes the following: Berm A circular ridge of soil constructed around the base of a newly transplanted tree to hold water. 1. Installing a berm. After firming the soil, a water-retaining wall or ridged structure called a berm may be installed by using the excess soil to form a ring around the trunk (Figure 17–10). This structure forms a basin to hold water around the base of the tree. 2. Mulching. A mulch should be placed around the base of the stem to control weeds and retain moisture in the bare soil. Mulching also prevents the soil from cracking and aids in soil infiltration by water and rapid root development. 3. Staking and anchoring (or guying). Balled and burlapped seedlings are often selfsupporting. Newly planted tree seedlings, especially bare-root seedlings, are prone to toppling by the wind. Without additional support, the tree may be tilted 530 Chapter 17 Installation of the Landscape